Method for counting sheets of paper and apparatus

ABSTRACT

A method and an apparatus for counting the numbers of piled up sheets of paper by means of a sensing device including a probe, wherein said probe runs, for scanning thereof, along a slanted slope defined by the side edge portions of piled up sheets of paper, each of which sheets is shifted a little aside from the lower one in succession for arrangement of their side edges in tiers, and oscillation of said probe, during scanning, is converted into an electric signal to achieve counting of numbers of sheets of paper thereby.

United States Patent [1 1 Igarashi et al.

[ 1 Jan. 21, 1975 METHOD FOR COUNTING SHEETS OF PAPER AND APPARATUSInventors: Takeo Igarashi; Tadao Takeuthi, both of Tokyo, JapanAssignee: Dai Nippon Printing Company Limited, Tokyo, Japan Filed: July30, 1973 Appl. No.: 384,144

Foreign Application Priority Data July 29, 1972 Japan 47-76104 June 5,1973 Japan 48-63187 U.S. Cl. 235/92 SB, 235/92 PK, 235/92 R,

235/98 Int. Cl. G06m 9/00 Field of Search 235/92 SB, 92 PK, 98 RReferences Cited UNITED STATES PATENTS Potter 235/92 SB 3,694,630 9/1972Dybel 235/92 PK Primary Examiner-Gareth D. Shaw AssistantExaminer-Joseph M. Thesz, Jr.

Attorney, Agent, or FirmWoodhams, Blanchard & Flynn [57] ABSTRACT Amethod and an apparatus for counting the numbers of piled up sheets ofpaper by means of a sensing device including a probe, wherein said proberuns, for scanning thereof, along a slanted slope defined by the sideedge portions of piled up sheets of paper, each of which sheets isshifted a little aside from the lower one in succession for arrangementof their side edges in tiers, and oscillation of said probe, duringscanning, is converted into an electric signal to achieve counting ofnumbers of sheets of paper thereby.

6 Claims, 14 Drawing Figures Patented Jan. 21, 1975 5 Sheets-Sheet 1 v 1FIG Patented Jan; '21, 1975 I 5 Sheets-Shee t s i l I I I I I I I I I II I I I I I l I I v $2525 32 52 5 @224 gums 52:5 Nmw 5 v m 8n m v 6 i zl NO NE :m m 8 Y mm m m FIlIJII I I I I I I I I i I I I I l I I I i I II I I I i I Patented Jan. 191s s Shgts-Sheet 4.

4 Fla "8A A FIG. B FIG. ac

Patented 1m. 21, 1975' 3,862,402.

' 5 Sheets-Sheet 5 FIG. 9

' I H F:

METHOD FOR COUNTING SHEETS OF PAPER AND APPARATUS BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention relates to amethod for counting in a simplified way the numbers of piled up sheetsof paper and an apparatus therefor.

2. Description of the Prior Art To count the numbers of piled up sheetsof paper, there has hitherto been used such a means either that thesheets of paper are taken out one by one from the piled stack fortransport to a suitable counting device, or that the sheets of paper areturned over one by one by the humans hand for counting thereof. v Ineither instance, however, there has been a remarkable difficulty incounting the numbers of piled up sheets of paper with desiredeffectiveness. And this has been the noticeable disadvantage of theprior art.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a method for counting the numbers of piled up sheets of paperand an apparatus therefor, which are capable of counting the numbers ofpiled up sheets of paper with a good efficiency and which are free fromsuch a disadvantage of inefficiency as possessed by the conventionalmethod as well as the apparatus therefor.

Another object of the present invention is to provide a method forcounting the numbers of piled up sheets of paper and an apparatustherefor, wherein the numbers of sheets of paper is counted in asimplified way but with exactness by means of a counting apparatuscomprising a sensing device having a probe said probe is to be kept incontact with'the sheets of paper in order to scan along a slanted slopedefined by the side edge portions of sheets of paper. Each of the sheetsis shifted a little aside from the lower one in succession forarrangement of the sheet side edge portions in tiers. Said probe isadapted to initiate oscillation every time it drops from one side edgeportion of a sheet to that of the next lower one during scanningthereof. Every oscillation is converted into an electric signal, wherebythe numbers of the sheets of paper is counted.

A further object of the present invention is to provide an apparatus,for counting the numbers of piled up sheets of paper, having a sensingdevice comprising a piezo electric element and a probe possessed of aspring effect. The piezo electric element and probe are disposed withinthe sensing device in such a manner that the piezo electric element ispositioned in parallel with the probe with a predetermined intervaltherebetween and the top end the piezo electric element is connectedwith a portion of the probe through the intermediate of a cushionrubber. The base end portions of both the probe and the piezo electricelement are fixedly connected to each other. A set of said probe andpiezo electric element are supported by a support ing member at thefixing point where said base end portions connect and at a point on theprobe just extended toward the top end thereof from the fixing pointbetween a middle portion of the probe and the top end portion of thepiezo electric element, through the intermediate of the supportingrubbers. The apparatus is capable of counting the numbers of piled upsheets of paper very exactly, the probe being adapted to make anaccurate response to the arrangement in tiers of sheets of paper of verylittle thickness. Moreover, the apparatus is capable of manufacture atvery low cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing away of counting the numbers of piled up sheets of paper by means of anapparatus of the present invention, wherein a first preferred embodimentof sensing device is provided.

FIG. 2 is an enlarged front view of a sensing device included in theapparatus shown in FIG. I.

FIG. 3 is a partially cross-sectional side view of the sensing deviceshown in FIG. 2.

FIG. 4 is a block diagram of an electronic counter of the countingapparatus shown in FIG. 1.

FIG. 5 is a view illustrating an electric circuit of the sensing deviceprovided within the counting apparatus.

FIG. 6 is a view illustrating a waveform of the output from a piezoelectric element.

FIG. 7 is a view for illustration of a waveform mode within a waveshaping circuit of the sensing device shown in FIG. 1.

FIG. 8A, 8B, and 8C are the views illustrating varied waveformsinitiated in a wave shaping circuit of the sensing device shown in FIG.1.

FIG. 9 is a partially sectional front view illustrating a secondpreferred embodiment of sensing device provided in a counting apparatusaccording to the present invention.

FIG. 10 is a fragmentary, partially cross-sectional front view on anenlarged scale of the sensing device shown in FIG. 9.

FIG. 11 is a left-end view of the portion of the sensing device shown inFIG. 10.

FIG. 12 is a cross-sectional front view of a piezo electric elementportion of the sensing device shown in FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, reference character adenotes the sheets of paper piled up on a table 0 in such a manner thateach sheet is shifted a little aside from the lower one in successiontoward the foremost top of the stack, whereby all the side edge portionsof the shifted-a-little-aside sheets of paper are arranged in tiers band cooperate to form a slanted slope.

A first embodiment of a sensing device I of the present invention usablein counting the number of sheets of paper piled up as above-described.

Said sensing device 1 comprises a case 2 made of aluminium. A probe 3 ofphosphor bronze is inserted into a small hole 5 defined in the foremostend portion of said case 2 and is held therein by an intermediatecushion rubber 4. The probe has an end portion thereof projectedoutwardly from said small hole 5. A crystal piezo electric element whichis disposed within the expanded hole 6 of the case and is supported bysupporting rubbers 7, 8. The piezo element is pressed toward said probeto result in contact between one end portion thereof and the rear end ofsaid probe. A wave shaping circuit 10 is arranged within the cavity 11of the case and has an electrical connection to the other end of said.piezo electric element, a counting switch 13, and a clear switch 14.

The above-described sensing device I is connected to an electroniccounter 25 through a lead line 12 connected with said wave shapingcircuit at one end thereof.

Said electronic counter 25 is provided with a power switch 26, anone-round-count indicating window 27, a total-count indicating window28, a clear switch 29, a foot switch 30, and a gate switch 31. Said footswitch can be used in place of said clear switch 29, since the footswitch is to function just the same as the clear switch does.

The electric circuit arranged within the electronic counter 25 is shownin FIG. 4, wherein the numerical references 15, and 15" denote singleplace counters for the one-round counting. For instance the firstcounter counts the figure in the first place, a second one the figure inthe second place, and a third one the figure in the third place,respectively.

The numerical references 16, 16', and 16" denote the respective decodersconnected with said counters l5, 15' or 15". Each above-mentioneddecoder is connected to an indicator tube 17, 17 and 17", respectively.

The numerical references 18, 18', 18" denote respective single placecounters for the total count. For instance, the first counter isallotted to figures only in the first place, the second one to figuresonly in the second place, and the third one to figures only in the thirdplace.

The numerical references 19, 19, 19", denote respective a decodersconnected to said counters 18, 18', 18" individually. Each of saiddecoders is connected with an indicator tube, 20, 20', 20", provided inthe indicating window 28.

A numerical reference 21 denotes a timer, 22 denotes a gate circuit, 23denotes a pulse generator, and 24 denotes AND gate circuit.

FIGS. 9 through 12 illustrate a second preferred embodiment of sensingdevice of the counting apparatus according to the present invention.

With provision of a second preferred embodiment of sensing device inplace of the first one, the counting apparatus of the present inventioncan perform counting work in the same way as with the first preferredembodiment. Therefore, the following description is directedspecifically to the second preferred embodiment of sensing device.Without repeating the above description of other parts of the countingapparatus.

The case 33 of the sensing device 32 is of bakelite, and in the outer,or sensing, end portion thereof, there is defined a contact plate 34that is slanted to an imaginary, horizontal plane by -50 and is providedwith a slit 35 through which a probe 36 projects outwardly. The rear endof said probe is attached to a sensing member 37 as described later on.

The outer end portion of the probe 36 is bent downwardly and projectsoutwardly from said slit 35 sufficiently to scan along the tiers b ofthe slanted slope defined by side edge portions of sheets of paper a.

In addition, the outer, or foremost, end portion of the probe 36 is hereof stainless material. When too narrow in its width and too pointed, itmay not only harm the sheets of paper but may also be hampered in itseffectiveness in scanning. Accordingly, it is desirable for the probe 36to have thickness of I00 p. and width of l m/m in the outer end portionthereof. All other portions of the probe, except the outer end portion.are here of phosphor-bronze plate material, possessed of a spring effect(i.e. which is resilient) with thickness of 0.2 m/m and width of 2 m/m.

Said sensing member 37 includes a pipe 38 held within and fixedlyattached to the case 33. Supporting rubbers 39, 40 are inserted intoeach end portion of the pipe 38. That is, said supporting rubber 40supports the middle portion of the probe 36, while said supportingrubber 39 supports the base end portion thereof.

The positive side of the sensing member 37 is connected to a waveshaping circuit 51 and a preamplifier 42 through the intermediate of acontact member 41 disposed within the case 33, while the negative sidethereof is connected directly to the case 33. The preamplifier 42 isconnected with the line 12.

A numerical reference 43 denotes a piezo electric element disposedwithin said pipe 38 in parallel with the probe 36 at a predeterminedinterval. The base end portion of the piezo element 43 is fixedlyconnected to the base end portion of the probe 36 by means of solderingor bonding so that both base end portions are supported in turn by thepipe 38 through the intermediate of the supporting rubber 39.

Further, the outer end portion of said piezo electric element 43 is,within the pipe 38, fixed to a portion of the probe 36 through a cushionrubber 44, here of silicon rubber. The piezo electric element is here 21eeramic bimorph.

As seen in FIG. 12, said piezo electric element 43 comprises a pair ofceramic plates 48, 49 coated with a damp-proofing paint 47 on the outersurface thereof, a reinforcement metal plate 50 held between said pairof ceramic plates, and output lines 45, 46 consisting of silver ribbonsoldered to said ceramic plates.

OPERATION To count the number of piled up sheets of paper with the aidof the first preferred embodiment of the present invention, at first thepower switch 26, gate switch 31 and either the clear switch 29 or thefoot switch 30 are turned on and all the indication tubes 17, 17', 17"as well as 20, 20', 20", are turned back to indicate a figure of 0.

Subsequently, as seen in FIG. 1, the outer, or foremost, end of thesensing device 1 is put onto the slanted slope defined by the side edgeportions of the sheets of paper a piled up on the table c. The paper isso piled that each sheet is shifted a little aside from the lower one insuccession for arrangement of said side edge portions in tiers c, sothat the probe 36 of said sensing device comes in contact with theslanted slope to scan therealong at the scanning rate of 30 sheets persecond.

Then the probe 3 initiates oscillation every time it drops from one sideend portion of the sheet onto that of the next lower one. Thisoscillation of the probe effects a pressure toward the piezo electricelement 9, whereby said piezo electric element generates an electricsignal with such a A.C. waveform as shown in FIG. 6.

With regard to this waveform, it can be said that the period ofoscillation in the initial phase remarkably differs from that in thefinal phase. This is because the period of oscillation in the initialphase is influenced mainly by the natural oscillation of piezo electricelement itself. However, due to a rapid decrement thereof, the period ofoscillation in the later phase depends only the oscillation of the probeitself, whereby there occurs a noticeable change with regard to theperiod of oscillation.

The thus resulted output is fed, without any modification, into a waveshaping circuit (FIG. 5) as an input thereof. That is, the input isapplied to the base of preamplifier transistor Q1, an emitter follower.Accordingly, the output waveform from the emitter follower Q has nonegative values, as seen in FIG. 7. And then this output is transmittedto the base of transistor Q through resistance R and condenser CWhenever no input is fed thereto, the collector potential of transistor0 stays always positive, as seen in FIG. 8A, but swings toward thenegative when an input is applied thereto.

Upon this change of potential the base potential of transistor Q becomesbiased toward the negative to so remarkable an extent that the collectorvoltage of transistor O is changed into the negative values.Accordingly, the input is converted to a positive pulse, as seen in FIG.88, by passing through an integration circuit comprising resistance Rand condenser C The latter pulse is fed into a monostable multivibratorcomprising transistors Q Q and Q wherein is generated a positive outputpulse with a width determined by the time constant of resistance R andcondenser C as shown in FIG. 8C. Said positive output pulse is to have asufficient width, or on time, to cover and thus invalidiate all theother oscillations initiated by any other causes in the system. Thewidth of such positive output pulse, i.e. its on time should not belarge enough to overlap the next output pulse to be generated as theprobe drops down to the next tier of the sheet pile. The width of thepositive output pulse should be determined, for instance, as to be 2 3milli seconds.

Passing through the lead line 12, as shown in FIG. 1, the resultingoutput pulse is fed into the electronic counter 25, wherein digitalcounting is performed by the count circuit shown in FIG. 4.

When an one-round-count is required, indicator tubes 17, 17', 17"indicate figures on the one-roundcount through the one-round-countindicating window. When the multi-rounds counts are required,,a switchfor the total count (not shown) should be turned on and then theindicator tubes for the total count will indicate figures for the totalsum up of each one-roundcount, along with the indication of theone-roundcount.

A further description will be given hereinunder with regard to a way tocount the numbers of piled up sheets of paper by means of a secondpreferred embodiment.

A disadvantage of the first preferred embodiment of the sensing deviceis that a piezo electric element thereof is not capable of generatingelectricity with a high enough efficiency, whereby provision of anamplification circuit is required to increase the applied voltagetherein, with no regard for a higher cost thereof, since the probe 3 isadapted to effect an up-and-down movement to inflict only a lengthwisepressure upon the piezo electric element along the axis thereof. Thesecond preferred embodiment is however improved to eliminate theabove-mentioned disadvantage therefrom.

The thus improved sensing device 32 is placed onto the slanted slopedefined by the side edge portions of piled up sheets of paper in thesame manner as in the case of the first preferred embodiment, in orderthat the probe 36 scans therealong with its foremost end portion to bebrought into contact with said slanted slope.

When the foremost end of the probe 36 moves along the slope arranged intiers b, that is, from the side edge portion of one sheet a to that ofthe lower sheet, as shown in FIG. 10 from a position illustrated by abroken line to that by a solid line, the probe 36 is inflicted a shockwhich initiates an oscillation of the probe 36.

This oscillation is applied to the piezo electric element 43 through theintermediate of the fixing point f within the supporting rubber 39 andthe fixing points e, d of the cushion rubber 44.

It is through the cushion rubber portion 44 that the oscillation of theprobe is largely applied to the piezo electric element 43. At its endadjacent the fixing point f to the supporting rubber 39, a strain occursin the piezo electric element in proportion with the magnitude ofoscillation of the probe 36 initiated by the shock, producing thevoltage seen in FIG. 6.

On this occasion, the supporting rubbers 39, 40 absorb the naturaloscillation of the probe 36, but do not intercept transmission ofoscillation initiated by the shock of the probe.

Provision of the cushion rubber 44 leads the movement of the piezoelectric element 43 as well as the probe to be centered around thefixing point f, in the same direction with the same phase; accordingly aslow and gentle movement of the probe 36 effects a slow and gentlemovement of the piezo electric element that results in a very smalloutput therefrom.

Thus, it can be said that provision of the cushion rubber 44 is veryadvantageous in that it can serve to magnify the difference between theoutput due to the oscillation initiated by the shock of the probe andany output resulting from other causes except said shock.

The aforementioned shock initiates an up-and-down oscillation of theprobe 36. Meanwhile, the fixing points d, e, f defined between the probeand cushion rubber 44, between the piezo electric element 43 and cushionrubber 44, and between the supporting rubber 39 and the probe, togetherwith the piezo electric element, are induced to oscillate by said shock.As a rule, however, a mode of oscillation is to be determined by thedistance between the fulcrums; in this regard, the oscillation betweeneach fulcrums d, e, f cooperate to form an integrated oscillation to beapplied to the piezo electric element 43.

With reference to FIG. 10, it can be understood that it is the naturaloscillation of a closed loop of e 44 d 36 f 43 e that determines thewaveform of the electric output.

Application of the thus effected oscillation to the piezo electricelement 43 induces the latter to generate an output with such a waveformas seen in FIG. 6, in a similar manner to the piezo electric element 9of the first embodiment. The thus generated output is fed into theelectronic counter 25 by line 12 through the intermediate of thewave-shaping circuit 51 and preamplifier 42, for achievement of thedigital counting and indication of the result therefrom.

The practical utilization of this preferred embodiment of the presentinvention proves that an output of 2 5 V is obtainable from piled upsheets of paper with thickness of 0.15 m/m, and an output of 3 7 V fromthe sheets with thickness of 0.24 m/m.

Even from counting the numbers of sheets of paper as thin as 0.1 0.25mm, there may be obtained a result as accurate as nearly 100 percent.

Although particular preferred embodiment of the invention have beendisclosed hereinabove for the purpose of illustration, it will beunderstood that variations or modifications thereof which lie within thescope of the invention as defined by the appended claims are fullycontemplated.

For example, provision of a rotary switch to the electronic counter maysuitably change resistance within the wave shaping circuit, as required,so as to accord with the counting of the sheets with varying thickness,for instance, such as thin, mediumly thin, mediumly thick, and thicksheets. Further, the lead line 12 of the sensing device can bepreferably connected with a control box of electronic counter throughthe intermediate of a connector.

What is claimed is:

1. An apparatus for counting a number of piled up sheets of papercomprising:

a sensing device having a case, a probe disposed oscillatably withinsaid case and with the foremost end of said probe projecting outwardlyfrom the case, and a piezo electric element disposed in said case, saidpiezo electric element being connected to said probe so as to generatean electric signal due to oscillation of said probe, said probe beingresilient, said piezo electric element being positioned parallel withthe probe with a predetermined space therebetween, an interveningcushion rubber connecting the foremost end of said piezo electricelement to an intermediate portion of said probe, said probe and piezoelectric element both having base end portions, said base end portionsbeing fixedly attached to each other at a fixing point, spacedsupporting members in said case, said base end portions beingelastically supported by one said supporting member at said fixingpoint, said probe including a portion slightly offset from saidintermediate probe portion toward said foremost probe end andelastically supported by the other said supporting member; and anelectronic counter connected with said sensing device to count signalstransmitted from said piezo electric element in order to indicatefigures for the counted number of sheets.

2. The apparatus of claim 1 in which the foremost end of the casedefines a slanted, plate-like wall having a slit, the foremost end ofsaid probe being bent downwardly and extending through said slitsufficiently to scan along the side edge portions of the piled up sheetsadjacent said plate-like case wall, said other supporting member beingspaced inboard in said case from said slanted foremost end wall, saidprobe extending freely from said other supporting member through saidslit.

3. The apparatus of claim 2 in which the foremost end of said probe isabout p. thick and about one mm wide, the remainder of said probe beingabout 0.2 mm thick and about 2 mm wide.

4. The apparatus of claim 3 in which said foremost end portion of saidprobe is of stainless material, the remainder of said probe being ofphosphor bronze plate.

5. The apparatus of claim 2 including hollow pipelike means fixedlyattached within said case, said supporting members being fixed at eachend of said pipelike means, said piezo electric element and the adjacentportion of said probe and said cushion rubber all being disposed withinsaid pipe-like means, said pipe-like means being spaced from theforemost end of said case, wave shaping circuit means disposed in saidcase rearwardly of said pipe-like means for applying the output of saidpiezo electric element remotely to said electric counter.

6. The apparatus of claim 1 including a wave shaping circuit connectingthe output of said piezo electric element to the input of saidelectronic counter, said wave shaping circuit being adapted to bedisposed within said case, said wave shaping circuit including means forremoving half cycles of one polarity from the piezo electric elementoutput waveform and further means for converting the resultant waveformto an array of one or more pulses and still further including amonostable multi-vibrator timed for producing, from said last mentionedpulses, a single output pulse for each sheet edge struck by said probe,said output pulse being sufficiently long to mask the later phases ofpiezo electric element output oscillation, but not overlapping the nextoutput pulse to be generated from striking of a new sheet edge portionby the probe, said supporting members permitting transmission of theoscillation initiated by the shock of probe contact with a new sheetedge portion but thereafter absorbing part of the continued probeoscillations, whereby to damp the natural oscillation of the probe.

1. An apparatus for counting a number of piled up sheets of papercomprising: a sensing device having a case, a probe disposedoscillatably within said case and with the foremost end of said probeprojecting outwardly from the case, and a piezo electric elementdisposed in said case, said piezo electric element being connected tosaid probe so as to generate an electric signal due to oscillation ofsaid probe, said probe being resilient, said piezo electric elementbeing positioned parallel with the probe with a predetermined spacetherebetween, an intervening cushion rubber connecting the foremost endof said piezo electric element to an intermediate portion of said probe,said probe and piezo electric element both having base end portions,said base end portions being fixedly attached to each other at a fixingpoint, spaced supporting members in said case, said base end portionsbeing elastically supported by one said supporting member at said fixingpoint, said probe including a portion slightly offset from saidintermediate probe portion toward said foremost probe end andelastically supported by the other said supporting member; and anelectronic counter connected with said sensing device to count signalstransmitted from said piezo electric element in order to indicatefigures for the counted number of sheets.
 2. The apparatus of claim 1 inwhich the foremost end of the case defines a slanted, plate-like wallhaving a slit, the foremost end of said probe being bent downwardly andextending through said slit sufficiently to scan along the side edgeportions of the piled up sheets adjacent said plate-like case wall, saidother supporting member being spaced inboard in said case from saidslanted foremost end wall, said probe extending freely from said othersupporting member through said slit.
 3. The apparatus of claim 2 inwhich the foremost end of said probe is about 100 Mu thick and about onemm wide, the remainder of said probe being about 0.2 mm thick and about2 mm wide.
 4. The apparatus of claim 3 in which said foremost endportion of said probe is of stainless material, the remainder of saidprobe being of phosphor bronze plate.
 5. The apparatus of claim 2including hollow pipe-like means fixedly attached within said case, saidsupporting members being fixed at each end of said pipe-like means, saidpiezo electric element and the adjacent portion of said probe and saidcushion rubber all being disposed within said pipe-like means, saidpipe-like means being spaced from the foremost end of said case, waveshaping circuit means disposed in said case rearwardly of said pipe-likemeans for applying the output of said piezo electric element remotely tosaid electric counter.
 6. The apparatus of claim 1 including a waveshaping circuit connecting the output of said piezo electric element tothe input of said electronic counter, said wave shaping circuit beingadapted to be disposed within said case, said wave shaping circuitincluding means for removing half cycles of one polarity from the piezoelectric element output waveform and further means for converting theresultant waveform to an array of one or more pulses and still furtherincluding a monostable multi-vibrator timed for producing, from saidlast mentioned pulses, a single output pulse for each sheet edge struckby said probe, said output pulse being sufficiently long to mask thelater phases of piezo electric element output oscillation, but notoverlapping the next output pulse to be generated from striking of a newsheet edge portion by the probe, said supporting members permittingtransmission of the oscillation initiated by the shock of probe contactwith a new sheet edge portion but thereafter absorbing part of thecontinued probe oscillations, whereby to damp the natural oscillation ofthe probe.